package com.ysten.basic.common.utils.persistence;

import java.util.Collection;
import java.util.List;

import javax.persistence.criteria.CriteriaBuilder;
import javax.persistence.criteria.CriteriaQuery;
import javax.persistence.criteria.Path;
import javax.persistence.criteria.Predicate;
import javax.persistence.criteria.Root;

import org.apache.commons.lang3.StringUtils;
import org.springframework.data.jpa.domain.Specification;

import com.google.common.collect.Lists;
import com.ysten.basic.common.utils.Collections3;
 

public class DynamicSpecifications
{
	public static <T> Specification<T> bySearchFilter(final Collection<SearchFilter> filters,
			final Class<T> clazz)
	{
		return new Specification<T>()
		{
			@Override
			public Predicate toPredicate(Root<T> root, CriteriaQuery<?> query,
					CriteriaBuilder builder)
			{
				if (Collections3.isNotEmpty(filters))
				{

					List<Predicate> predicates = Lists.newArrayList();
					for (SearchFilter filter : filters)
					{
						// nested path translate, 如Task的名为"user.name"的filedName,
						// 转换为Task.user.name属性
						String[] names = StringUtils.split(filter.fieldName, ".");
						Path expression = root.get(names[0]);
						for (int i = 1; i < names.length; i++)
						{
							expression = expression.get(names[i]);
						}

						// logic operator
						switch (filter.operator)
						{
						    case EQ:
				                predicates.add(builder.equal(expression, filter.value));
				                break;
				            case NE:
				                predicates.add(builder.notEqual(expression, filter.value));
				                break;
				            case LIKE:
				                predicates.add(builder.like(expression, "%" + filter.value + "%"));
				                break;
				            case NOTLIKE:
				                predicates.add(builder.notLike(expression, "%" + filter.value + "%"));
				                break;
				            case GT:
				                predicates.add(builder.greaterThan(expression, (Comparable)filter.value));
				                break;
				            case LT:
				                predicates.add(builder.lessThan(expression, (Comparable)filter.value));
				                break;
				            case GTE:
				                predicates.add(builder.greaterThanOrEqualTo(expression, (Comparable)filter.value));
				                break;
				            case LTE:
				                predicates.add(builder.lessThanOrEqualTo(expression, (Comparable)filter.value));
				                break;
				            case IN:
				                String[] values = filter.value.toString().split(",");
				                predicates.add(expression.in(values));
				                break;
				            case NOTIN:
				                String[] values1 = filter.value.toString().split(",");
				                predicates.add(builder.not(expression.in(values1)));
				                break;
				            case ISNULL:
				                predicates.add(builder.isNull(expression));
				                break;
				            case ISNOTNULL:
				                predicates.add(builder.isNotNull(expression));
				                break;
						}
					}

					// 将所有条件用 and 联合起来
					if (!predicates.isEmpty())
					{
						return builder.and(predicates.toArray(new Predicate[predicates.size()]));
					}
				}

				return builder.conjunction();
			}
		};
	}
}